update prompt

app.py

@@ -1000,13 +1000,13 @@ Thought: you should always think about what to do and consider previous and subs
 Action:
 ```
 {{
-    \"action\": $TOOL_NAME,
-    \"action_input\": "the input to the action"
+    "action": should be one of [{tool_names}],
+    "action_input": "the input to the action"
 }}
 ```
 Observation: the result of the action.
 
-$TOOL_NAME should be one of [{tool_names}]
+
 If **Thought**, **Action** is missing in the response of using tools, you must re-write the response.
 
 ---\n When you are able to provide final answer, you must use the following format to output "Thought", "Action" (json blob):
@@ -1015,8 +1015,8 @@ Thought: I know what to respond
 Action:
 ```
 {{
-    \"action": \"Final Answer\", 
-    \"action_input": \"Final response to human\"
+    "action": "Final Answer", 
+    "action_input": "Final response to human"
 }}
 ```